In one aspect this invention relates to a fluid measurement and collection device. In another aspect this invention relates to an improved balance bar type blood measurement device which includes the use of a hollow balance bar containing mobile weights which accentuate the rotative cut off action of the balance bar. In still another aspect this invention relates to a blood measurement device which may be easily attached and disattached to either vertical or horizontal bases during use. A further aspect of this invention is that the device may be easily adjusted so that it is positioned in a plane level to the ground thereby facilitating accurate measurement. A still further aspect of the subject invention relates to a fluid dispensing device which can dispense a predetermined quantity of fluid from a fluid container and automatically shut off the fluid supply after the preset quantity of fluid has been dispensed.
Advances in medical technology have made it possible to store blood over extended periods of time for use in surgical operations, or transfusions and the like, as needed. This capability to store blood has made it possible to create blood reserves containing blood collected from donors. Apparatus and procedures for the efficient collection of blood have thus become important in the effort to maintain the flow of blood from donors to those in need. It is generally known that a blood donor should not be allowed to donate more than a specific quantity of blood at one time. The quantity of blood which donors may give at one time varies with the physical conditions of the donor.
In the past, donors were personally attended by medically trained personnel who monitored the donation process. With the advent of "blood banks," however, more efficient donation procedures were desired. One problem was solved by providing an apparatus which would automatically stop the flow of blood from a donor once a specified quantity had been collected. The subject invention relates to an improved type of blood collection measurement device which performs that function.
The most common method of blood collection includes the use of flexible tubing connected with a needle, which is inserted in a blood vessel of a patient's arm for example, and a blood container, such as a plastic bag. Several devices have been made which measure the weight or quantity of the blood collected and at a preselected point stop the flow of blood from the donor to the container by closing off the flexible tubing.
In blood collection, devices which employ a balancing arm to accomplish shut off of the flexible tubing upon rotation of the balancing arm from a level position several operational problems have been encountered. The primary problem is that the unaided rotation of the balance bar, occasioned only by the moment of the blood container at one end of the bar surpassing the moment of a counter weight at the other end of the bar, is relatively slow. This slow rotation is, of course, a result of a slow rate of flow of blood through the flexible tubing into the container. The slow rotation in turn causes the constriction of the flexible tubing to be accomplished slowly resulting in inaccuracies of measurement.
Another problem with balance bar type measurement devices is that they must be carefully leveled with respect to the ground in order for the balancing mechanism to be performed accurately. Accordingly, some of the balance bar type measuring devices now available are provided with their own stand which will insure a level plane for the balance bar so long as the stand itself is placed on a level surface. Inaccuracies may still result, however, if the chosen surface is not level, and in some cases, it may be difficult to find a convenient level surface on which to place the stand. Examples of such prior art devices include those disclosed in U.S. Pat. No. 3,698,494, U.S. Pat. No. 3,557,789, Canadian Pat. No. 581,426, and U.S. Pat. No. 2,784,932.